1. Field of the Invention
The present invention relates to a fast fill valving mechanism for a master cylinder, particularly a master cylinder which has a short length and compact structure.
2. Description of the Prior Art
Master cylinders usually require an initial period of actuation that produces a hydraulic pressure and fluid displacement which places the wheel brakes in position for the initiation of braking. In other words, a certain amount of hydraulic fluid must be displaced by the master cylinder through the system in order to merely place the pistons and associated brake equipment in position for the initiation of braking. It is highly desirable to provide a master cylinder construction which when actuated effects a quick or "fast fill" of the associated brake lines and braking apparatuses so that the brakes are ready immediately for the commencement of braking. The result is a more quickly responsive braking system because the fast fill construction eliminates a longer brake pedal stroke necessary for effecting the displacement of fluid within the brake system. Prior master cylinder constructions providing for a "fast fill" of the braking system typically include a ball valve and other such devices. These structures are speed sensitive because a slow actuation of the brakes permits fluid leakage through the valving and thus fails to effectively accomplish the desired transmittal of brake fluid to the brake system. U.S. Pat. Nos. 4,559,781 and 4,718,234 illustrate types of flexible sealing mechanisms for a master cylinder having a fast fill function. It is desirable to provide a fast fill mechanism for a short master cylinder which will provide solutions to the above problems and which will be easily assembled and cost less than prior fast fill master cylinder constructions.